Multirotors for the Beginner

Written by Jim T. Graham
Born to Fly
Column
As seen in the March and May 2013 issues of Model Aviation.

Multirotors are all the rage. I know this because I run RCGroups.com, the world’s largest RC site, and the multirotor section is blowing up with activity.

Another reason I know that multirotors are pretty happening right now is that Stephen Cinch (aka “SleepyC") has gone practically quadcopter crazy. I’ve been following Sleepy’s progress and reading posts on RCGroups. After a while, the pressure was too much and I had to have one.

I found a local pilot who had a 550-size multirotor and was willing to swap it for one of my airplanes. The problem is that I know nothing about multirotors other than they have four or more rotors and a board, that they fly similar to a helicopter, and that people like to use them for photography and video.

I decided to talk with SleepyC and get some advice from the quad-crazy man about how to get started in multirotor flying.

JG:What is the best way to get started in the world of multirotors?

SC: Right now, several great manufacturers produce some ready-to-fly smaller quadcopters that are perfect to learn with. They have all the basics of a quadcopter, and they’re actually more agile, so they require your thumbs to really get some training.

They’re small enough that if you have a problem, you can simply cut the throttle. They really won’t break. Having one will give you the opportunity to learn how to fly the machines before you start investing in the bigger ones, so they’re a great place to start. Pretty much every manufacturer is jumping on the trend and offering one.

The RealFlight flight simulator also has some quadcopters you can fly. This allows you to get your orientation going before you put your real quad in the air.

This is a quadcopter that can be flown on the RealFlight RC Flight Simulator. Practice your quadcopter flights worry free!

A generic quadcopter is available in Expansion Pack 8 (sold separately). It has an onboard camera positioned underneath which pans with the knob and tilts with the three-position switch. One cool way to use that is to open up a viewport within the main view and set it to use that camera.

JG:What are the price points on multirotors?

SC: They can be pretty inexpensive if you have your own transmitter, as most of us do. There are some ready-to-fly ones that are approximately $100. Some that are transmitter-ready are roughly $69. They’re relatively affordable considering that most things in my Giant Scale part of the hobby run into the thousands of dollars.

JG:Because I have a 550 size, would it be a good idea to get one of the smaller ones to play with before I start flying the 550 or should I jump right in?

SC: Well, it all depends on your experience. If you’ve flown for quite some time and have a little helicopter experience, you can jump right in. But if you have access to a simulator and practice with a helicopter a little while you learn about the multirotors, you shouldn’t have problems.

JG:Let’s say that I get a little micro quad. What are all the skill sets I need? I’m slightly intimidated by what appears to be a ton of things about which I need to be knowledgeable.

SC: Well, basically, it’s like any other part of the hobby. You’re going to have to do some research and reading. There are so many different ways that you can go with this. There are multiple configurations: quadcopters, hexacopters, octocopters, and Y6-copters. They all fly differently, and there are so many different controller boards to choose from.

There are plug-n-play setups where you build the quad up to specs and load the software onto a laptop, and then it’s pretty straightforward. There are also some controller boards that are open source. Groups of designers write programming for them. You really can get into it as deeply as you want.

JG:That’s what I have, but it sounds slightly intimidating, and it makes me want to go to a retailer and buy a preprogrammed board.

SC: That’s one thing that is pretty cool about multirotors. In a docile setting, they are pretty forgiving, and a lot of them will nearly hover by themselves.

You can go as stable as you want or as aggressive as you want. Some of the pilots who are doing aerobatics are doing just the opposite—where it’s so loose that they can do multiple flips 5 inches off the ground. You basically have to be a skilled helicopter pilot for that, though.

JG:What safety issues do I need to be aware of? When I’m setting this up, I have this vision of me strapping it to the table or something.

SC: All you have to do is take the propellers off. You aren’t gonna hurt or burn up anything by starting them up with the propellers off, and it’s recommended that you do that. That way, if the motor starts up you can grab it with your hand and feel if it’s right or wrong, but without the possibility of slicing yourself. That’s the safe way to set it up.

JG:Let’s say that I’m feeling good about everything. What do you do for orientation once that thing gets up in the air? How do you know what’s front and what’s back?

SC: As you get more involved in multirotors, you learn what you can get away with. I started off with some tape on the front. I was flying the X configuration, which means that there are two motors in the front that are facing forward. I put a little tape around those.

When I was flying around and kind of getting the hang of it, it was fine as long as the tape was visible. But when you’ve got one up in the air 20 or 30 feet, and you’re looking into the horizon, it turns into a gray blob.

I put lightweight LED strips on the motors. You can get them nearly anywhere. Most of the quads run on three- or four-cell LiPos, and when you set the LEDs up, all you have to do is plug the LEDs straight into the balance cord of your battery. There’s no extra battery weight, and they’re only going to drain approximately 100 to 200 milliamps.

LED lights help with orientation.

Set up red in the front, blue in the back, or whatever configuration you like, and it makes all the difference. Even in bright sunlight, at 11.1 volts, you can really see those lit-up LEDs and find the orientation. A bonus is that instantly you have a night-flying rig!

Last week was one of the first times I took mine out, and it was awesome. It was easier to see at night than it was in the day. There’s no mistaking which direction you’re headed.

JG:Tell me about your flying style. I know that you can go crazy with this thing, but if you wanted to do photos or video, the real trick is to fly smoothly and easily. Tell me how you make that happen.

SC: You set up how much correction happens from the gyros in the quadcopter and how much throw, or how much increased motor pitch you’re going to get from that side of the quad. You could simply tune down the gains or the stick scaling, which is similar to adding exponential. You’re basically telling it that you don’t want your stick as sensitive as it could be.

On a popular board, such as the KK2, stick scaling up goes up to 150. Many of the aerobatic pilots are setting it at 115-130, which makes for a very sensitive quad. That’s what you need to be able to do the flips, inverted flight, and death bombs toward the earth, flipping over at the last second.

I had a quad similarly set up, but I enjoy the settings in which the stick scaling is down at 30. I’m trying my best to fly as smoothly as possible and take out any vibrations so I can get good video with the smaller quad.

Whatever style you’re going to do, RCGroups is exploding right now with activity about quads. I found myself frequently visiting the RCGroups forums, and there was information everywhere.

Nearly everything I’ve learned so far has been from RCGroups. Often, when I got stuck, I would type something into the search engine and there would be eight or 10 threads about it.

JG:How did your first flight go?

SC: I was pretty amazed. I had a friend with me who had flown several in the past. He came up and flew it approximately a foot off the ground and double-checked that everything was correct. I couldn’t believe how stable it was. We had it toned down, but still not as toned down as I have them for video flying now. It was pretty easy. If you have RC experience, it’s not that hard.

If you are interested in aerial video or photography, there are a few controller boards that are called IO [Intelligent Orientation]. When you power up the quad, it knows which way the front of the quad is by the position of the board.

When IO knows where the front of the quad is, you don’t have to worry about your orientation. When you push your stick, it somehow figures out which way you want to go. No matter which direction the quad is pointing, if you need the quad to go left and you hit the stick left, it will move left.

JG:I want that! That sounds really cool.

SC: You can turn that off with a switch on your radio. If you’re flying like normal and you get confused, you hit that switch, it goes to IO, and you can drive it back.

The pinnacle of a hobbiest is this audio visual (AV) rig, the DJI Flame Wheel F550. By adding a two-axis gimbal, the F550 becomes a capable AV machine.

JG:What do the boards cost?

SC: The standard aerobatic board is approximately $400. But if you want to add GPS, that’s roughly another $400. The GPS has a return-to-home function. If it loses signal for some reason or if you get freaked out and need it to come home, you can hit a switch, and it will return on its own.

The big brother to that is the NAZA M, which is basically a straight-up autopilot system. It’s what many professional photographers use. It has settings that you can set up on the computer such as pan, tilt, etc.

You can even do a thing called “point of interest.” If you wanted to film your house, for example, you’d go to the front of the house, hit a button, tell it that the front door is a point of interest, and program it from a laptop to do whatever maneuver automatically and land itself.

JG:I built a nice helicopter once, but I immediately sold it because I figured I’d crash it and cost myself $200 or $300. How much money do you lose if you crash one of these midsize quadcopters?

SC: With some of the more aerobatic quads, or even a smaller one, you could make a mistake and plow it into the ground and maybe break a propeller or two. If you’re getting into trouble and it gets out of hand and you cut the throttle, you’ll do yourself a favor. You’ll probably break an arm, and arms are $5 or $6. Propellers regularly break.

JG:What should I look for in propellers?

SC: You want really good, balanced propellers. That’ll make all the difference in the performance of the quad. Unless you have a complete failure, (which I experienced recently), you can usually come out unscathed.

Unlike airplanes or other aircraft, if you have a failure at altitude, these do not glide. So it would be similar to dropping it off of a building. I had a complete radio failure at approximately 220 feet, and it turned over and fell straight onto the pavement. It was not a good day for me. It broke everything on it. There wasn’t one usable piece left.

A budget version of the classic FPV Explorer is stable, with plenty of front-arm width for your favorite FPV camera setup.

JG:Get a broom and a dust pan.

SC: Literally. It hit on all four motors exactly. It couldn’t have landed any flatter. It destroyed all of the motors, the electronics, and the entire frame burst into 42 million pieces. It was probably the worst failure you could possibly have. I lost a GoPro [camera] that day, too.

JG:That brings us to our next subject: cameras. Do I have to buy a $300 GoPro?

SC: No, there are a whole bunch of options. It depends on what you want to do. If you want to do it for fun and shoot video of your friends or your house, there are keychain cameras as low as $25 that you can find on the Internet. There are other companies that are making HD [high-definition] cameras that range from 720 to 1,080 pixels. Some of the most popular ones are the GoPros, especially now that they’ve come out with the Hero 3.

The lens, the case, and all of its parts allow it to take some abuse. That’s one of the appeals of the GoPro. RC Logger has several models of HD cameras, and there’s a new one on the way that has a [two-axis] gyroscope built into it.

JG:So you’ve been using these quad and camera setups to cover RC events?

SC: I keep reconfiguring what I’m using, but I’ve even used the Gaui 330, which can barely tote a GoPro, but it did it!

JG:If you wanted to post some decent-quality stuff on the Internet, what would you suggest for a camera?

SC: You would want higher than 120 dpi and as fast of a frame rate as you could afford. One of the main things that I’m finding out that has been a problem for everyone since the beginning is called a “jello.”

When you go up, the vibrations in the quad add jiggle to your video. Although the video can be clear at times, it has a wave-rippling effect that goes through the video from the vibrations affecting the chips inside the cameras. A lot of pilots say that if you can go to 60 frames per second instead of 30, you are capturing more data in between the vibration and that helps take it out.

The more you balance your propellers, the fewer vibrations you will have. It’s an ongoing adjustment. There are hundreds of threads on RCGroups theorizing this.

I’ve had some success with a certain camera mount. I think I’m going to start making my own mount that basically hangs itself off of some foam and isolates where the camera mount is in relation to the quad to keep any vibration coming from the mechanical parts from going into the camera.

JG:Before first-person view (FPV) ever hit, I had a friend show me one of the first units and let me fly an EasyStar with goggles. I wish I had gotten into it then. It’s interesting to me. What about this 550 in an FPV application?

SC: It depends on what you want to do. For a short-range FPV setup, you’re talking a few hundred bucks now. Some of the technology that’s come out in the last year is pretty amazing.

My buddy is into FPV, and he had little modules so that he could have on-screen display. Basically, everything was ready to go for $150. Then he just had to get all of the little antennas and receivers.

If you want to add FPV to a quad, you’re probably looking at an additional $400 investment. This stuff is really rugged, so it’s probably not going to break, and you can use it for a while.

With some of the cameras for FPV, you can use your GoPro by hooking it into the system. But there are specific-timed, lightweight FPV cameras that go on the front of these things. Some of the frames that you can buy are modified to be able to snap the cameras in and not add much weight. They’re a few hundred dollars.

You can find videos of these pilots on RCGroups or YouTube. Some of them are so good at this stuff now. They know their quads well enough that they’re flying 30 or 40 mph through forests. That’s the kind of thing that’s becoming huge due to the availability of the equipment.

My friend had his FPV up a few weeks ago, and I just watched through the goggles. It is a really cool experience to feel like you’re flying like Superman.

JG:What would you say to anyone out there who wants to be an FPV pilot, but has no idea where to start?

SC: Don’t buy something off the cuff. Do a lot of research and figure out what your goal is. If you want to do photography or video, that’s one thing; FPV is another. Right now there are several things that can kind of do it all, but they aren’t necessarily the best for anything. The ones that are specialized for their purposes are going to do a better job for you.

Hopefully I have asked some of the questions that some of you have had. Although flying a multirotor or quadcopter requires some research, the same is true for any part of the RC hobby.

Every few years the hobby opens a new door of excitement, and I’m stoked to walk through this one!